Application Of Lightweight Concrete Research Articles

The Use of Recycled Polyethylene in Water-Oil Emulsion for Lightweight Concrete

This study was to determine the suitability of recycled waste polyethylene (WPE) processed into water-oil emulsion for lightweight concrete applications. The processed WPE in the form of polyethylene emulsion (PE-e) is to promote physical interaction between the polymeric material and the cementitious matrix. The PE-e used was also to partially replace concrete mix composition by PE-e_1, PE-e_2.5, PE-e_5, and PE-e_10 percents for reference concrete and to introduce plasticity into the mechanical behaviour of the concrete. The PE was processed into PE-e to promote affinity for water, and this hydrophilicity was prominent in PE-e_1 and PE-e_2.5 percent concretes. Concretes with PE-e_1 and PE-e_2.5 percent formed good miscibility with the cementitious matrix. The density of the PE-e concrete decreased to 13.68% with 10% PE-e at 28 days. The replacement of mix constituents of PE-e_1, PE-e_2.5, and PE-e_5 percent induced elastic to plastic behaviour in the concrete coupled with low water absorption. The FTIR data showed characteristic peaks of 3378 cm-1, 1740 cm-1, and 1148 cm-1 in the PE-e. Using optical microscopy, it was shown that the PE particles were homogenously dispersed in the concrete matrix. The study shows the feasibility of using PE-e_1 percent to produce structural lightweight concrete and up to PE-e_10 percent for nonstructural applications mainly for light non-load-bearing partitions.

Development of alternative disposals for waste rice husk and dredged harbor sediment by sintering as lightweight aggregates

ABSTRACT This study developed the alternative disposals for dredged harbor sediments by co-sintering with waste rice husk into lightweight aggregates (LWA) to benefit resource sustainability and waste valorization. The effects of rice husk addition and sintering temperature on LWA performances such as water absorption, particle density, crushing strength, weight loss, volume shrinkage, and open porosity were investigated. The key parameters (e.g. C/Fe ratio in raw materials) controlling the LWA performances and engineering applications were determined. Results showed that dredged harbor sediments could be made into suitable LWA for engineering applications from the controlled rice husk addition and sintering temperature. The addition of rice husk led to lower LWA particle density, but raised water absorption and reduced crushing strength. The increase of sintering temperature reduced water absorption and improved crushing strength. The aggregates with 10–15% rice husk, sintered at 1150 °C had appropriate particle density (1.60–1.73 g/cm3), water absorption (11.8–16.6%), and crushing strength (6.0–10.6 MPa), which could be suitable for lightweight concrete applications. Low water-soluble chloride and heavy metals leachabilities aligned with Taiwan’s regulatory standards for concrete aggregates. Co-treating waste rice husk and dredged harbor sediment into LWA can benefit the waste reduction and circular economy, and reduce the environmental impacts associated with their disposals.

Shear strengthening of high strength lightweight SCC beams internally reinforced with GFRP bars and external CFRP strips

Last few years have seen a substantial growth in the development and application of lightweight concrete (LWC) due to its enhanced mechanical properties and economic benefits in comparison to conventional normal weight concrete (NWC). The use of LWC in infrastructure has been popularised, especially in long-span bridges and high-rise bridges due to its lower density, which significantly reduces the dead load on the structure. Carbon fibre reinforced polymers (CFRP) and glass fibre reinforced polymers (GFRP) have rapidly gained acceptance in the infrastructure industry for their desirable characteristics over traditional steel. Extensive experimental research has been carried out over to years to investigate the shear performance of externally strengthened NWC beams with CFRP (carbon fibre reinforced polymer) strips. However, very limited research has been conducted on the shear performance of GFRP reinforced LWC beams externally strengthened with CFRP strips. Therefore, the main objective of this experimental study is to investigate the shear performance of high strength lightweight self-compacting concrete (HLWSCC) beams reinforced with internal GFRP bars and strengthened with external CFRP strips. HLWSCC is the latest development in concrete technology that combines the benefit of LWC and self-compacting concrete (SCC). One control specimen and two shear deficient HLSCC beams were strengthened with CFRP strips in the shear span. The test variable studied was the strip orientation (u-wrap and 45°) and all beams subjected to static four-point bending test. Load-deflection response and failure modes were observed and recorded for all the tested specimen. CFRP strips has considerably increase the load carrying capacity of HLWSCC strengthened beam specimen. The percentage increase in nominal shear strength ranged from 58.7% to 73.4% over unstrengthened control specimen.

Mechanical Behavior of Corroded Steel in Lightweight Concrete: A Review

There is an immediate need for reinforced concrete (RC) construction to protect natural resources and environmental sustainability due to a gradual decline in natural resources and a problem in many waste disposal sites used. Reducing natural stones as aggregates in concrete using agriculture waste as aggregate to produce lightweight concrete is an effective way to reduce this problem. Lightweight concrete applications for structural design have long been applied because they significantly benefit design and construction costs. However, limited information about the structural performance, such as the bond strength, the compressive strength can be a barrier to applying lightweight concrete in the construction industry, as inadequate bond strength can result in structural deficiencies in RC structures. Therefore, to launch the use of lightweight concrete as a general material of construction, this research was conducted to review the current information on the mechanical behaviour of corroded lightweight concrete structures, while agricultural solid wastes were used as a lightweight aggregate in the concrete mixture.

Thermal performance of lightweight concrete applications in building envelopes in Lebanon

Innovative building materials are being used in building envelopes for reducing their heating and cooling needs. This paper aims to assess the thermal impact of using lightweight concrete in Lebanese building constructions by pouring an 8 cm thickness of lightweight concrete on the roof and the slab and replacing traditional hollow concrete block by lightweight concrete blocks. Thermal properties of two different samples were experimentally determined: the first one (558 kg/m3) used for the roof and the slab and the second one (1074 kg/m3) used for the walls. Then numerical simulations were carried out for a Lebanese traditional detached house using the characteristics of these two samples. The thermally improved Light Weight Concrete building (LWC) was compared to a traditional Lebanese house base case (BC) using a dynamic building energy simulation tool in the four different Lebanese climate zones: coastal, mid-mountain, mountain, and inland zones. The results highlight the effectiveness of integrating LWC to building envelopes by reducing energy consumption and improving thermal comfort in both winter and summer climate conditions and in the different Lebanese climatic zones. The paper demonstrates that the use of LWC in the vertical walls replacing the traditional hollow blocks can reduce the heating needs by up to 9% and by up to 13% for cooling needs. On the other hand, adding a LWC roof screed has a very high impact on cooling and heating energy consumption, which can reach up to 74% in cooling energy savings and up to 24% in heating energy savings.

High strength flowable lightweight concrete incorporating low C3A cement, silica fume, stalite and macro-polyfelin polymer fibres

Lightweight concrete (LWC) can reduce the self-weight of structures and can save material and labour costs in industry. Despite these merits, the application of lightweight concrete is mostly limited because of low compressive strength, often <60 MPa; and low workability, due to high absorption capacity and possibility of aggregates floating in the case of high water to binder ratio. In this paper, an innovative lightweight concrete was developed with high compressive strength (>90 MPa) and high workability (slump flow value > 550 mm). The workability, mechanical properties, durability, microstructure and aggregates distribution of the high strength flowable lightweight concrete (HFLWC) were investigated. Key mix parameters were examined including Portland and low C3A cements, fly ash (FA), undensified silica fume (UDSF), river sand and silica sand. Stalite was used as a high performance lightweight coarse aggregate. In addition, four volume fractions of macro-polyfelin polymer fibres (MPP), 0.5%, 1%, 1.5% and 2%, were added to investigate the effect on the flexure strength and different durability indicators. It was found that the incorporation of stalite, low w/b ratio, low C3A cement and UDSF can produce LWC with exceptional strength and flowability. The results showed that HFLWC could be produced with density <2000 kg/m3, slump flow of 750 mm, compressive strength of 98 MPa at 28 days and 105 MPa at 56 days. In addition, ductility was improved more than fourfold by increasing MPP from 0.5% to 2%. And new hydration and strength models were developed based on hardened concrete test results and were found suitable for HFLWC. The SEM results showed that the ITZ between the non-pre-treated stalite and the matrix was extremely fine and very dense.

LEED Study of Green Lightweight Aggregates in Construction

Decreasing the demand for natural aggregates is doubly justified by the significant contribution of the construction industry to the unsustainable development path of the natural environment, and the projected global increase of the consumption of construction aggregates. Extensive research has been carried out on the physical and mechanical properties of concrete which incorporates plastic as aggregates; yet, no single study has been able to draw on structured research which demonstrates the improved sustainability performance of plastic-based aggregates to support sustainable development in the construction industry for a project seeking Leadership in Energy and Environmental Design (LEED) certification. The goal of this research is to explore the potential benefits that green processed lightweight aggregates (PLA) can provide to a project seeking LEED certification in accordance with the requirements of LEED v4 for Building Design and Construction. The objectives are to: (1) determine which LEED credit requirements can be met through using the studied material; (2) provide a comprehensive analysis of the applicable attainable LEED credits, given the existing technical information of the selected material, and (3) provide guidelines to maximize further credit attainment. To this end, the findings indicated that the use of PLA as a total replacement for coarse aggregates in lightweight concrete applications would contribute to earning directly up to 8 points (out of 110 total points) towards LEED certification. Such significant number allows for the potential increase of the project’s certification by one level. This is the first study of its kind to investigate the improved sustainability performance of recycled plastic aggregates from a LEED point of view. Moreover, the guidelines provided by the research will enable developers to maximize the financial and environmental benefits of their buildings through the reduced lifecycle cost and the enhanced LEED score. This research should encourage project teams to incorporate the knowledge of sustainable practices, and play an active role in sustainable development.

Characterization of processed lightweight aggregate and its effect on physical properties of concrete

The plastic because of its lightweight and flexibility to adopt the required shapes has led in an enormous increase in production of plastic products during recent years. To minimize the negative environmental impacts of plastic waste, many industrial sectors have tried to recycle and utilize the plastic waste. Among the other sectors, concrete industry can be considered as one of the alternatives such as to use the recycled plastic as aggregate replacement in concrete. A processed lightweight aggregates (PLA) has been manufactured using the plastic waste and other local materials using a compression moulding press technique. The detailed characterization of the PLA was also conducted. In addition, the effect of PLA incorporation on the physical properties of concrete along with effect of curing temperature on the compressive strength was also tested. The addition of manufactured aggregate in concrete has increased the Poisson’s ratio, thermal conductivity values while the density, and compressive strength were found to be reduced as compared to control mix. It was also noticed that PLA concrete can be cured at temperatures up to 30 °C, without significantly affecting compressive strength. The PLA has shown the prospective to be used in lightweight concrete applications.

Lightweight concrete of continuous structure without fine aggregate

The study deals with basic properties and area of application of lightweight concrete of continuous structure without fine aggregate. When fine aggregate is excluded from the concrete structure, it becomes lightweight, has lower thermal conductivity and cost, simpler production technology. It also has durability sufficient for wall panels, water resistance, frost resistance and a number of other indicators. The paper describes additives used for concrete air entrainment. Using these additives does not complicate the production technology of panels, the panels can be easily transported and have sufficient stability and durability upon storage. The article justifies effective application of light concrete with continuous structure without fine aggregate in low-rise construction. Light concretes of continuous structure without fine aggregate allow to completely exclude the use of fine aggregate, to sharply reduce density and thermal conductivity of concrete, as well as to reduce moisture content and humidity of products, improve their cohesion and workability and get a number of other benefits. The study shows that light concrete without fine aggregate numerous advantages prove that it will be used in construction practice for a long time.

Developing Fire Resistant Construction for Tunnel Construction Using Lightweight Aggregate Concrete

The article describes partial results of the research of fire and technical properties of lightweight concrete with regard to the possibility of the application of lightweight concrete in tunnel structure wall lining. The article summarises partial results of individual parts of the project focused on the specification of material properties, execution of temperature analysis of the fire resistance, calculation of structure heat transmission and specification of the thermal response of the material as subject-matter to the research.

Effects of polypropylene twisted bundle fibers on the mechanical properties of high-strength oil palm shell lightweight concrete

In this study, the effects of a new type of non-metallic fiber (polypropylene twisted bundle (PPTB)) on the slump and mechanical properties of oil palm shell (OPS) concrete have been investigated. The results showed that increasing the volume fraction of PPTB fibers, it slightly decreases the workability and density of the concrete. It has found that the compressive strength of OPS concrete increases with increasing PPTB fiber volume fraction. The results revealed that the reinforcement of OPS concrete with steel and PPTB fibers reduces the strength loss of OPS concrete in poor curing environments. In addition, the fiber with low volume fraction (up to 0.25 %) is more efficient in improving the flexural strength of OPS concrete compared to its splitting tensile strength. The average modulus of elasticity (E value) is obtained to be 17.4 GPa for all mixes, which is higher than the values reported in previous studies and is within the range for normal weight concrete. The performance of the PPTB fibers is comparable to that for steel fibers at a volume fraction (V f) of 0.5 %, which provides less dead load for lightweight concrete. The findings of this study showed that the PPTB fibers can be used as an alternative material to enhance the properties of OPS concrete. Hence, PPTB fibers are a promising alternative for lightweight concrete applications.

Investigation into the mechanical properties of structural lightweight concrete reinforced with waste steel wires

The study of concrete incorporating different waste fibres has started to increase rapidly due to economic reasons and positive environmental effects. In the study reported here, waste steel wires from steel reinforcement and used formworks were blended with structural lightweight concrete, with the aim of replacing commercial steel fibres of controlled quality with recycled fibres. Compression, tensile, flexural and impact tests were performed to assess the mechanical properties of 28 d old concrete specimens reinforced with mixed waste steel wires, mixed steel fibres as well as plain concrete. The percentages of fibres examined in the fibre reinforced concrete (FRC) specimens were 0·25%, 0·50% and 0·75% (volume fraction of the concrete). With varying fibre contents, similar trends were observed in all the types of FRCs studied. It was thus concluded that waste steel wires could be used as a suitable alternative to industrial steel fibres for structural lightweight concrete applications.

Technical and Economical Efficiency for Application of Nanomodified High-Strength Lightweight Concretes

The development of construction technologies is impossible without the proper estimation of economical efficiency. Some results of technical and economical efficiency of the developed high-strength structural lightweight concretes are presented in the article. Overview concerning world practice of research and application of lightweight concrete composition are made. The main properties and advantages of developed energy efficient high-strength lightweight concretes are described. The method of calculation of economic efficiency of concrete by means of reduction of total construction weight and increasing of floors’ number is proposed. Dependence between efficiency, footprint of building and number of floors is presented. It is shown that economical calculation for developed material which is based only on the cost of the material itself does not allow to obtain adequate data concerning prospect and competitiveness of the material. The authors offer method of calculating the economic efficiency of the developed high-strength lightweight concrete which takes into account the technical properties of the new material. The results of the study showed that the application of high-strength lightweight concrete is more effective than traditional kinds of the concretes.

Influence of the Steel Fiber Length on the Properties of Lightweight Concrete

Lightweight aggregate concrete has lower density and lower elasticity modulus, so it has better earthquake resistance. But the low strength limited the application of lightweight concrete. Steel fiber can improve the strength of lightweight aggregate concrete. In this paper, the influences of different lengths of steel fiber on the slump, compressive strength, splitting tensile strength and antiflex cracking strength are investigated. The results show that adding steel fiber reduces the workability of the concrete mixture, but it improved the each strength of light weight concrete and different lengths have the different regularity of effects.

Reviews on the Properties of Aggregates Made with or without Geopolymerisation Method

Aggregates are popular for use in concrete and lightweight concrete applications. Recent research shows that the by-product materials such as fly ash can be used as raw material in producing aggregates and lightweight aggregates. The usage of this material can improve the quality of the aggregates produced compared to conventional in term of structurally strong, physically stable, durable, and environmentally inert. This paper summarized the process and mechanical testing on the fly ash aggregates and lightweight aggregates to be used in concrete.

Spatial Textile Reinforcement Structures for Ventilated and Sandwich Facade Elements

Textile Reinforced Concrete (TRC) is a new composite material using mesh-like technical textiles to transfer tensile forces in a concrete member. The main advantage in using these reinforcements is the reduction of concrete covers to only few millimeters leading to slender and light-weight concrete applications like ventilated facade elements and sandwich panels with TRC facings. Based on three applications, which are realized in the last two years, it is revealed that there is a need not only for capable planar fabrics but also for spatial structures. Inherently stable reinforcement structures are achieved by impregnating the fabrics with a resin (e.g. epoxy resin) and curing the structures in the desired shape at temperatures up to 180°C. Moreover, the utilization of the cross-section of the rovings is homogenized and, thus, a tensile strength up to 1400 MPa is achieved for AR-glass fabrics. The article deals with selected applications for facade structures made of TRC, material properties and demands on the textile reinforcement as well as production processes. Furthermore, test results regarding the load-bearing behavior of these selected applications are presented.

Connectors for Timber–Lightweight Concrete Composite Structures

In timberconcrete composite structures (TCCSs), a timber member is connected to a concrete slab so that the timber primarily resists tensile forces and the concrete resists compressive forces generated from flexure. In Europe, renovating historical timber floors to TCCS has become the most prevalent market for the usage of this technology. The addition of a concrete slab to a timber floor makes the system performance competitive to reinforced concrete floors. The horizontal timberconcrete interface is the challenge of the TCCS. Various connectors are on the market with a wide range of stiffnesses and load capacities which are crucial design parameters for TCCSs and empirically determined by tests. The results of push-out tests with five different connectors are presented. A lightweight concrete (LC) with a density of 1.6 kN/m3 (100 lb/ft3) was used as the concrete floor in the samples. The application of LC provides an interesting variation in TCCS technology to minimize the dead load on the timber floors. Results show that the combination of stiffness and capacity are crucial in choosing an economical connector.